Vending machines have not been standardized throughout the world. Rather, vending machines are as varied as the cultures of the countries in which the machines are located. For example, vending machines in Japan are very different than vending machines in the United States.
The Japanese culture is accustomed to buying a great many goods from a great variety of relatively sophisticated vending machines. The United States, in contrast, has a culture which is accustomed to purchasing a much smaller variety of goods from generally less sophisticated vending machines. The Japanese market tends to produce more sophisticated and more expensive hardware/architecture from which its vending machines are constructed. In contrast, the hardware of U.S. vending machines tends to be less sophisticated and less expensive.
At a basic level, vending machines throughout the world share similar attributes. For example, they all include a controller that controls the operation of numerous peripheral devices. These peripherals are connected to the controller via a communications bus. In the United States, the standard vending machine communications bus is the MDB standard, i.e., the "International Multi-drop Interface Standard," established by the National Automatic Merchandising Association (NAMA) of Chicago, Ill. As expected, this is not the vending machine communication standard in Japan. There, the standard appears to be the VCCS standard.
A universal characteristic of the market for machine-vended goods is that these markets are extremely sensitive to the hardware costs of the vending machine. A small difference in cost of the hardware for a given machine can greatly effect its profitability.
To use a Japanese bill and coin validation mechanism, for example, a U.S. machine requires the Japanese mechanism to be modified so that it can communicate using the MDB protocol rather than the VCCS protocol. Alternatively, a specialized adapter could be constructed to convert from the VCCS protocol to the MDB protocol so that the Japanese mechanism could be used without modification. Both of these techniques significantly raise the cost of using the Japanese mechanism or peripheral.
Another option for using a Japanese peripheral device in a U.S. machine would be to provide the U.S. machine with a controller having two serial ports. One of the ports would be dedicated to the MDB bus, while the other would be dedicated to the VCCS bus. Unfortunately, this requires a custom integrated circuit (IC) that has two serial ports. Such a customized IC is very expensive.
It is a problem to integrate vending machine peripheral devices of disparate communication standards, e.g., MDB and VCCS, into a single vending machine and yet still have acceptably low hardware costs given the extreme price sensitivity of the market for machine-vended goods.